Biosimilarity Assessment of 2 Filgrastim Therapeutics in Healthy Volunteers

This study aimed to compare the pharmacokinetic, pharmacodynamic, and safety profiles of a proposed biosimilar and innovator filgrastim therapeutics in healthy volunteers. In a crossover design, 23 subjects received a single subcutaneous injection of 300-µg filgrastim, followed by a 7-day washout period. Assessed pharmacokinetic parameters were the maximum observed filgrastim serum concentration (C_max ), time to reach C_max (t_max ), the area under the concentration-time curve (AUC), and elimination half-life. Pharmacodynamics were assessed by the maximum observed absolute neutrophil count effect (E_max ), t_max,E (time to reach E_max ), and the area under the effect of the absolute neutrophil count -time curve. The test/reference ratio (90% confidence intervals) of C_max of 0.992 (0.860-1.143), AUC_0-inf of 0.995 (0.891-1.111), E_max of 0.952 (0.841, 1.078), and area under the effect of the absolute neutrophil count -time curve from time zero to 96 hours of 0.939 (0.854-1.032), were all well within the predefined equivalence boundaries of 80% and 125%. Obtained values for t_max (∼4 hours), t_max,E (∼15 hours), and elimination half-life (∼3.5 hours) were comparable between 2 treatment groups. The local tolerability and incidence of adverse events were comparable, with no clinically meaningful difference between biosimilar and innovator products. Altogether, the results suggested a high similarity of the proposed biosimilar to the innovator filgrastim in healthy volunteers.